Hello,

You could try to do it that way, but if the head is already off the engine it isn't such a big job to pull the cam.
If it were my engine I would certainly do that.
Not only to identify the cam, but also to check for any unusual wear and to inspect the cam retainer flange that is mounted directly behind the cam gear.
Most of the time it is worn (the bronze ones, the steel B18 items are much better) and allows the cam to travel back and forth, making cam timing erratic and also producing a irritating clatter.
While doing that also inspect the fiber cam gear, if it is still the original one it is almost certain it has become worn and brittle.

Make sure that when you take out the lifters you put them back in on the same postions, they MUST be on the same cam lobe they were before, otherwise your cam and lifters won't last long.

B.R

Stefan